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CPC Unified Gauge-Based Analysis of Daily Precipitation over CONUS

Daily files have been converted to unpacked netCDF4-classic from netCDF3, packed.

Brief Description:

  • CPC .25x.25 Daily US Unified Gauge-Based Analysis of Precipitation,

Temporal Coverage:

  • Daily 1948/01/01 to 2006/12/31: measurement accumulated to 12z of the day. (Real-time (RT) analysis available after 2006.)
  • Monthly 1948/01 to present (dates after 2006 are part of the real-time RT analysis.)
  • Long Term Means of daily, monthly for years 1981 to 2010.

Spatial Coverage:

  • 0.25 - degree latitude x 0.25 - degree longitude US grid (300x120).
  • 20.125N-49.875N, 230.125E-304.875E.


  • N/A

Update Schedule:

  • Static

Download/Plot Data: (FTP Access)

Variable Statistic Level Download File Create Plot/Subset
Precipitation Daily Total Surface See List plot
' ' Monthly Average Surface precip.V1.0.mon.mean.n plot
Precipitation Daily Long Term Mean Surface precip.V1.0.day.ltm.nc plot
' ' Monthly Long Term Mean Surface precip.V1.0.mon.1981-2010.ltm.nc plot

Usage Restrictions:

  • None

Detailed Description:

  • This data set is part of products suite from the CPC Unified Precipitation Project that are underway at NOAA Climate Prediction Center (CPC). The primary goal of the project is to create a suite of unified precipitation products with consistent quantity and improved quality by combining all information sources available at CPC and by taking advantage of the optimal interpolation (OI) objective analysis technique. The gauge analysis here covers the Conteminous United States on a fine-resolution and is quantitatively consistent with that covering the global land on a coarser resolution. See their CPC's data docs for more details or email them.

    Landmask is such that actual data resides between 20N-49.5N (lat grids 1-118) and 233.75E to 292.75 (lon grids 56-292).

    Values are for over the continental US. Data is daily from 1948-2006. Values are accumulated from 12z of the day before to 12z of the day (with no missing grids ).A land-sea mask is supplied.


  • Monthly data past 2006 includes real time (RT)files.

Related File Naming & Structure Information:

File Names:

  • precip.yyyy.nc for daily  (In directory: /Datasets/cpc_us_precip/)
  • precip.time,statistic.nc for monthly, long term means  (In directory: /Datasets/cpc_us_precip/)

OpenDap File Names:

  • /thredds/dodsC/Datasets/cpc_us_precip/precip.yyyy.nc for daily  

Dataset Format and Size:

  • PSL standard NetCDF 37 Mbyte file for each yearly file (packed).
  • PSL standard NetCDF 37 Mbyte file for each daily long term mean file (packed).
  • PSL standard NetCDF 62 Mbyte file for each monthly file (packed).
  • PSL standard NetCDF 1 Mbyte file for each monthly long term mean file (packed).

Missing Data:

  • No missing data over the CONUS. There are missing in the sourrounding box (-9.96921e+36).


  • Please note: If you acquire CPC US Unified Precipitation data products from PSL, we ask that you acknowledge us in your use of the data. This may be done by including text such as CPC US Unified Precipitation data provided by the NOAA/OAR/ESRL PSL, Boulder, Colorado, USA, from their Web site at / in any documents or publications using these data. We would also appreciate receiving a copy of the relevant publications. This will help PSL to justify keeping the CPC US Unified Precipitation data set freely available online in the future. Thank you!


  • (Interpolation algorithm) Xie_et_al_2007_JHM_EAG.pdf Xie, P., A. Yatagai, M. Chen, T. Hayasaka, Y. Fukushima, C. Liu, and S. Yang (2007), A gauge-based analysis of daily precipitation over East Asia, J. Hydrometeorol., 8, 607. 626.
  • (Gauge Algorithm Evaluation) Chen_et_al_2008_JGR_Gauge_Algo.pdf Chen, M., W. Shi, P. Xie, V. B. S. Silva, V E. Kousky, R. Wayne Higgins, and J. E. Janowiak (2008), Assessing objective techniques for gauge-based analyses of global daily precipitation, J. Geophys. Res., 113, D04110, doi:10.1029/2007JD009132.
  • (Construction of the Daily Gauge Analysis) Chen_et_al_2008_Daily_Gauge_Anal.pdf Chen, M., P. Xie, and Co-authors (2008), CPC Unified Gauge-based Analysis of Global Daily Precipiation, Western Pacific Geophysics Meeting, Cairns, Australia, 29 July - 1 August, 2008.

Original Source:


  • Physical Sciences Laboratory: Data Management
    325 Broadway
    Boulder, CO 80305-3328